Various balloon catheter designs have been developed for use in a wide range of medical procedures, such as angioplasty dilatation, stent delivery and localized drug delivery. One of the basic catheter designs for use in these medical procedures is known as an "over-the-wire" balloon catheter.
Conventional "over-the-wire" angioplasty dilatation catheters generally comprise an elongated catheter shaft having a proximal end and a distal end. The catheter includes an expandable balloon located at the distal end of the catheter tube. The catheter shaft typically defines an inflation lumen in fluid communication with the interior of the balloon which extends longitudinally to the proximal end of the catheter shaft. The catheter shaft also defines a separate guidewire lumen which extends longitudinally from the catheter shaft proximal end through the catheter shaft distal end.
Conventional "over-the-wire" angioplasty dilatation catheters are typically guided into position within the patient's vasculature through the use of a flexible guidewire having a diameter of approximately 0.010 to 0.018 inches and a length of about 180 centimeters. The distal end of the guidewire is extremely flexible so that it may be routed through the convoluted arterial pathway to the site of the stenosis. Once the distal portion of the guidewire is positioned across the treatment site, a conventional "over-the-wire" catheter may be threaded onto the guidewire by inserting the guidewire proximal end through the catheter guidewire lumen. With the balloon in a deflated state, the catheter is advanced through the patient's vasculature over the guidewire until the balloon is positioned across the treatment site. When it is desired to inflate the balloon, pressurized inflation fluid is injected into the proximal end of the inflation lumen via a syringe or other suitable pressure infusion device. As the pressurized inflation fluid travels through the inflation lumen and into the balloon, the balloon radially expands such that it presses against and opens the occlusion at the treatment site.
During a catheterization procedure, it may be necessary to thread a catheter on or off an indwelling catheter, or exchange an indwelling catheter for another catheter over an indwelling guidewire. To advance or withdraw a catheter over an indwelling guidewire, the physician must be able to grip the proximal portion of the guidewire extending outside the patient's body to maintain the position of the distal portion of the guidewire across the treatment site. However, the length of a conventional over-the-wire catheter, typically on the order of 135 centimeters, is greater than the length of the proximal portion of a standard guidewire which protrudes out the patient. Accordingly, it is necessary to extend the guidewire a sufficient distance outside the patient so that the physician may maintain his or her grip on the proximal portion of the guidewire while threading an over-the-wire catheter on or off an indwelling catheter. The additional length of guidewire needed is typically provided through the use of a guidewire extension which is temporarily "linked" or attached to the proximal end of the guidewire. Once the catheter has been threaded onto the guidewire extension and advanced over the guidewire through the patient's vasculature, the guidewire extension may be detached from the guidewire.
Alternatively, a long exchange wire on the order of 300 centimeters may first be guided through the patient's vasculature such that its distal portion is positioned across the treatment site. The catheter may then be advanced over the exchange wire without disturbing the position of the distal portion of the wire. After the catheter balloon is positioned at the treatment site, the exchange wire may be removed from the guidewire lumen and replaced with a shorter, easier to handle guidewire.
Therefore, there exists a need for an improved full-length guidewire lumen catheter device and method of use which enables exchange over a conventional-length guidewire without the use of extension guidewires or exchange wires.